# Description
The PR overhauls how IO redirection is handled, allowing more explicit
and fine-grain control over `stdout` and `stderr` output as well as more
efficient IO and piping.
To summarize the changes in this PR:
- Added a new `IoStream` type to indicate the intended destination for a
pipeline element's `stdout` and `stderr`.
- The `stdout` and `stderr` `IoStream`s are stored in the `Stack` and to
avoid adding 6 additional arguments to every eval function and
`Command::run`. The `stdout` and `stderr` streams can be temporarily
overwritten through functions on `Stack` and these functions will return
a guard that restores the original `stdout` and `stderr` when dropped.
- In the AST, redirections are now directly part of a `PipelineElement`
as a `Option<Redirection>` field instead of having multiple different
`PipelineElement` enum variants for each kind of redirection. This
required changes to the parser, mainly in `lite_parser.rs`.
- `Command`s can also set a `IoStream` override/redirection which will
apply to the previous command in the pipeline. This is used, for
example, in `ignore` to allow the previous external command to have its
stdout redirected to `Stdio::null()` at spawn time. In contrast, the
current implementation has to create an os pipe and manually consume the
output on nushell's side. File and pipe redirections (`o>`, `e>`, `e>|`,
etc.) have precedence over overrides from commands.
This PR improves piping and IO speed, partially addressing #10763. Using
the `throughput` command from that issue, this PR gives the following
speedup on my setup for the commands below:
| Command | Before (MB/s) | After (MB/s) | Bash (MB/s) |
| --------------------------- | -------------:| ------------:|
-----------:|
| `throughput o> /dev/null` | 1169 | 52938 | 54305 |
| `throughput \| ignore` | 840 | 55438 | N/A |
| `throughput \| null` | Error | 53617 | N/A |
| `throughput \| rg 'x'` | 1165 | 3049 | 3736 |
| `(throughput) \| rg 'x'` | 810 | 3085 | 3815 |
(Numbers above are the median samples for throughput)
This PR also paves the way to refactor our `ExternalStream` handling in
the various commands. For example, this PR already fixes the following
code:
```nushell
^sh -c 'echo -n "hello "; sleep 0; echo "world"' | find "hello world"
```
This returns an empty list on 0.90.1 and returns a highlighted "hello
world" on this PR.
Since the `stdout` and `stderr` `IoStream`s are available to commands
when they are run, then this unlocks the potential for more convenient
behavior. E.g., the `find` command can disable its ansi highlighting if
it detects that the output `IoStream` is not the terminal. Knowing the
output streams will also allow background job output to be redirected
more easily and efficiently.
# User-Facing Changes
- External commands returned from closures will be collected (in most
cases):
```nushell
1..2 | each {|_| nu -c "print a" }
```
This gives `["a", "a"]` on this PR, whereas this used to print "a\na\n"
and then return an empty list.
```nushell
1..2 | each {|_| nu -c "print -e a" }
```
This gives `["", ""]` and prints "a\na\n" to stderr, whereas this used
to return an empty list and print "a\na\n" to stderr.
- Trailing new lines are always trimmed for external commands when
piping into internal commands or collecting it as a value. (Failure to
decode the output as utf-8 will keep the trailing newline for the last
binary value.) In the current nushell version, the following three code
snippets differ only in parenthesis placement, but they all also have
different outputs:
1. `1..2 | each { ^echo a }`
```
a
a
╭────────────╮
│ empty list │
╰────────────╯
```
2. `1..2 | each { (^echo a) }`
```
╭───┬───╮
│ 0 │ a │
│ 1 │ a │
╰───┴───╯
```
3. `1..2 | (each { ^echo a })`
```
╭───┬───╮
│ 0 │ a │
│ │ │
│ 1 │ a │
│ │ │
╰───┴───╯
```
But in this PR, the above snippets will all have the same output:
```
╭───┬───╮
│ 0 │ a │
│ 1 │ a │
╰───┴───╯
```
- All existing flags on `run-external` are now deprecated.
- File redirections now apply to all commands inside a code block:
```nushell
(nu -c "print -e a"; nu -c "print -e b") e> test.out
```
This gives "a\nb\n" in `test.out` and prints nothing. The same result
would happen when printing to stdout and using a `o>` file redirection.
- External command output will (almost) never be ignored, and ignoring
output must be explicit now:
```nushell
(^echo a; ^echo b)
```
This prints "a\nb\n", whereas this used to print only "b\n". This only
applies to external commands; values and internal commands not in return
position will not print anything (e.g., `(echo a; echo b)` still only
prints "b").
- `complete` now always captures stderr (`do` is not necessary).
# After Submitting
The language guide and other documentation will need to be updated.
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Finishes implementing https://github.com/nushell/nushell/issues/10598,
which asks for a spread operator in lists, in records, and when calling
commands.
# Description
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This PR will allow spreading arguments to commands (both internal and
external). It will also deprecate spreading arguments automatically when
passing to external commands.
# User-Facing Changes
<!-- List of all changes that impact the user experience here. This
helps us keep track of breaking changes. -->
- Users will be able to use `...` to spread arguments to custom/builtin
commands that have rest parameters or allow unknown arguments, or to any
external command
- If a custom command doesn't have a rest parameter and it doesn't allow
unknown arguments either, the spread operator will not be allowed
- Passing lists to external commands without `...` will work for now but
will cause a deprecation warning saying that it'll stop working in 0.91
(is 2 versions enough time?)
Here's a function to help with demonstrating some behavior:
```nushell
> def foo [ a, b, c?, d?, ...rest ] { [$a $b $c $d $rest] | to nuon }
```
You can pass a list of arguments to fill in the `rest` parameter using
`...`:
```nushell
> foo 1 2 3 4 ...[5 6]
[1, 2, 3, 4, [5, 6]]
```
If you don't use `...`, the list `[5 6]` will be treated as a single
argument:
```nushell
> foo 1 2 3 4 [5 6] # Note the double [[]]
[1, 2, 3, 4, [[5, 6]]]
```
You can omit optional parameters before the spread arguments:
```nushell
> foo 1 2 3 ...[4 5] # d is omitted here
[1, 2, 3, null, [4, 5]]
```
If you have multiple lists, you can spread them all:
```nushell
> foo 1 2 3 ...[4 5] 6 7 ...[8] ...[]
[1, 2, 3, null, [4, 5, 6, 7, 8]]
```
Here's the kind of error you get when you try to spread arguments to a
command with no rest parameter:
And this is the warning you get when you pass a list to an external now
(without `...`):
# Tests + Formatting
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crates/nu-std"` to run the tests for the standard library
> **Note**
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> ```bash
> use toolkit.nu # or use an `env_change` hook to activate it
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Added tests to cover the following cases:
- Spreading arguments to a command that doesn't have a rest parameter
(unexpected spread argument error)
- Spreading arguments to a command that doesn't have a rest parameter
*but* there's also a missing positional argument (missing positional
error)
- Spreading arguments to a command that doesn't have a rest parameter
but does allow unknown arguments, such as `exec` (allowed)
- Spreading a list literal containing arguments of the wrong type (parse
error)
- Spreading a non-list value, both to internal and external commands
- Having named arguments in the middle of rest arguments
- `explain`ing a command call that spreads its arguments
# After Submitting
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# Examples
Suppose you have multiple tables:
```nushell
let people = [[id name age]; [0 alice 100] [1 bob 200] [2 eve 300]]
let evil_twins = [[id name age]; [0 ecila 100] [-1 bob 200] [-2 eve 300]]
```
Maybe you often find yourself needing to merge multiple tables and want
a utility to do that. You could write a function like this:
```nushell
def merge_all [ ...tables ] { $tables | reduce { |it, acc| $acc | merge $it } }
```
Then you can use it like this:
```nushell
> merge_all ...([$people $evil_twins] | each { |$it| $it | select name age })
╭───┬───────┬─────╮
│ # │ name │ age │
├───┼───────┼─────┤
│ 0 │ ecila │ 100 │
│ 1 │ bob │ 200 │
│ 2 │ eve │ 300 │
╰───┴───────┴─────╯
```
Except they had duplicate columns, so now you first want to suffix every
column with a number to tell you which table the column came from. You
can make a command for that:
```nushell
def select_and_merge [ --cols: list<string>, ...tables ] {
let renamed_tables = $tables
| enumerate
| each { |it|
$it.item | select $cols | rename ...($cols | each { |col| $col + ($it.index | into string) })
};
merge_all ...$renamed_tables
}
```
And call it like this:
```nushell
> select_and_merge --cols [name age] $people $evil_twins
╭───┬───────┬──────┬───────┬──────╮
│ # │ name0 │ age0 │ name1 │ age1 │
├───┼───────┼──────┼───────┼──────┤
│ 0 │ alice │ 100 │ ecila │ 100 │
│ 1 │ bob │ 200 │ bob │ 200 │
│ 2 │ eve │ 300 │ eve │ 300 │
╰───┴───────┴──────┴───────┴──────╯
```
---
Suppose someone's made a command to search for APT packages:
```nushell
# The main command
def search-pkgs [
--install # Whether to install any packages it finds
log_level: int # Pretend it's a good idea to make this a required positional parameter
exclude?: list<string> # Packages to exclude
repositories?: list<string> # Which repositories to look in (searches in all if not given)
...pkgs # Package names to search for
] {
{ install: $install, log_level: $log_level, exclude: ($exclude | to nuon), repositories: ($repositories | to nuon), pkgs: ($pkgs | to nuon) }
}
```
It has a lot of parameters to configure it, so you might make your own
helper commands to wrap around it for specific cases. Here's one
example:
```nushell
# Only look for packages locally
def search-pkgs-local [
--install # Whether to install any packages it finds
log_level: int
exclude?: list<string> # Packages to exclude
...pkgs # Package names to search for
] {
# All required and optional positional parameters are given
search-pkgs --install=$install $log_level [] ["<local URI or something>"] ...$pkgs
}
```
And you can run it like this:
```nushell
> search-pkgs-local --install=false 5 ...["python2.7" "vim"]
╭──────────────┬──────────────────────────────╮
│ install │ false │
│ log_level │ 5 │
│ exclude │ [] │
│ repositories │ ["<local URI or something>"] │
│ pkgs │ ["python2.7", vim] │
╰──────────────┴──────────────────────────────╯
```
One thing I realized when writing this was that if we decide to not
allow passing optional arguments using the spread operator, then you can
(mis?)use the spread operator to skip optional parameters. Here, I
didn't want to give `exclude` explicitly, so I used a spread operator to
pass the packages to install. Without it, I would've needed to do
`search-pkgs-local --install=false 5 [] "python2.7" "vim"` (explicitly
pass `[]` (or `null`, in the general case) to `exclude`). There are
probably more idiomatic ways to do this, but I just thought it was
something interesting.
If you're a virologist of the [xkcd](https://xkcd.com/350/) kind,
another helper command you might make is this:
```nushell
# Install any packages it finds
def live-dangerously [ ...pkgs ] {
# One optional argument was given (exclude), while another was not (repositories)
search-pkgs 0 [] ...$pkgs --install # Flags can go after spread arguments
}
```
Running it:
```nushell
> live-dangerously "git" "*vi*" # *vi* because I don't feel like typing out vim and neovim
╭──────────────┬─────────────╮
│ install │ true │
│ log_level │ 0 │
│ exclude │ [] │
│ repositories │ null │
│ pkgs │ [git, *vi*] │
╰──────────────┴─────────────╯
```
Here's an example that uses the spread operator more than once within
the same command call:
```nushell
let extras = [ chrome firefox python java git ]
def search-pkgs-curated [ ...pkgs ] {
(search-pkgs
1
[emacs]
["example.com", "foo.com"]
vim # A must for everyone!
...($pkgs | filter { |p| not ($p | str contains "*") }) # Remove packages with globs
python # Good tool to have
...$extras
--install=false
python3) # I forget, did I already put Python in extras?
}
```
Running it:
```nushell
> search-pkgs-curated "git" "*vi*"
╭──────────────┬───────────────────────────────────────────────────────────────────╮
│ install │ false │
│ log_level │ 1 │
│ exclude │ [emacs] │
│ repositories │ [example.com, foo.com] │
│ pkgs │ [vim, git, python, chrome, firefox, python, java, git, "python3"] │
╰──────────────┴───────────────────────────────────────────────────────────────────╯
```
# Description
These make it easy to make a Span that covers an entire argument and the
span of all arguments in a Call.
Call::arguments_span() is useful for errors where a command may accept
arguments or the pipeline, but not both.
Argument::span() is useful for errors where an arguments is incompatible
with one or more other arguments.
In particular, I wish to use this to create an error for an
implementation of #9563 that either allows arguments to set limits:
```nushell
limits set RLIMIT_NOFILE --soft 255 --hard 1024
```
Or pipeline:
```nushell
{name: RLIMIT_NOFILE, soft: 255} | limits set
```
But not both:
```
❯ [{name: RLIMIT_NOFILE, soft: 255, hard: 1024}] | limits set AS --soft 5 --hard 5
Error: nu:🐚:incompatible_parameters
× Incompatible parameters.
╭─[source:1:1]
1 │ [{name: RLIMIT_NOFILE, soft: 255, hard: 1024}] | limits set AS --soft 5 --hard 5
· ───────────────────────┬────────────────────── ──────────┬─────────
· │ ╰── or arguments, not both
· ╰── Supply either pipeline
╰────
```
# User-Facing Changes
Only nushell Command API changes
This PR reverts https://github.com/nushell/nushell/pull/9391
We try not to revert PRs like this, though after discussion with the
Nushell team, we decided to revert this one.
The main reason is that Nushell, as a codebase, isn't ready for these
kinds of optimisations. It's in the part of the development cycle where
our main focus should be on improving the algorithms inside of Nushell
itself. Once we have matured our algorithms, then we can look for
opportunities to switch out technologies we're using for alternate
forms.
Much of Nushell still has lots of opportunities for tuning the codebase,
paying down technical debt, and making the codebase generally cleaner
and more robust. This should be the focus. Performance improvements
should flow out of that work.
Said another, optimisation that isn't part of tuning the codebase is
premature at this stage. We need to focus on doing the hard work of
making the engine, parser, etc better.
# User-Facing Changes
Reverts the HashMap -> ahash change.
cc @FilipAndersson245
# Description
see https://github.com/nushell/nushell/issues/9390
using `ahash` instead of the default hasher. this will not affect
compile time as we where already building `ahash`.
# User-Facing Changes
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helps us keep track of breaking changes. -->
# Tests + Formatting
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# After Submitting
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Reverts nushell/nushell#8310
In anticipation that we may want to revert this PR. I'm starting the
process because of this issue.
This stopped working
```
let-env NU_LIB_DIRS = [
($nu.config-path | path dirname | path join 'scripts')
'C:\Users\username\source\repos\forks\nu_scripts'
($nu.config-path | path dirname)
]
```
You have to do this now instead.
```
const NU_LIB_DIRS = [
'C:\Users\username\AppData\Roaming\nushell\scripts'
'C:\Users\username\source\repos\forks\nu_scripts'
'C:\Users\username\AppData\Roaming\nushell'
]
```
In talking with @kubouch, he was saying that the `let-env` version
should keep working. Hopefully it's a small change.
# Description
Allow NU_LIBS_DIR and friends to be const they can be updated within the
same parse pass. This will allow us to remove having multiple config
files eventually.
Small implementation detail: I've changed `call.parser_info` to a
hashmap with string keys, so the information can have names rather than
indices, and we don't have to worry too much about the order in which we
put things into it.
Closes https://github.com/nushell/nushell/issues/8422
# User-Facing Changes
In a single file, users can now do stuff like
```
const NU_LIBS_DIR = ['/some/path/here']
source script.nu
```
and the source statement will use the value of NU_LIBS_DIR declared the
line before.
Currently, if there is no `NU_LIBS_DIR` const, then we fallback to using
the value of the `NU_LIBS_DIR` env-var, so there are no breaking changes
(unless someone named a const NU_LIBS_DIR for some reason).
# Tests + Formatting
~~TODO: write tests~~ Done
# After Submitting
~~TODO: update docs~~ Will do when we update default_env.nu/merge
default_env.nu into default_config.nu.
* Add source-env test for dynamic path
* Use correct module ID for env overlay imports
* Remove parser check from "overlay list"
It would cause unnecessary errors from some inner scope if some
overlay module was also defined in some inner scope.
* Restore Cargo.lock back
* Remove comments
* Initial implementation of ordered call args
* Run cargo fmt
* Fix some clippy lints
* Add positional len and nth
* Cargo fmt
* Remove more old nth calls
* Good ole rustfmt
* Add named len
Co-authored-by: Hristo Filaretov <h.filaretov@protonmail.com>
